The accepted method of identifying intrauterine fetal asphyxia is by fetal blood sampling to determine the blood pH. Present techniques require the direct trans-vaginal visualization of the fetal scalp or other presenting part using a fetal endoscope and an external light source. The skin is first cleansed with a swab to remove meconium and amniotic fluid and is then incised with a lancet until a free flow of blood occurs. A quick striking motion of the instrument is required to cut the skin. After the lancet is withdrawn, a capillary tube is inserted to draw off the blood sample. There are no means for retaining the endoscope in place during this procedure. This procedure is difficult, time consuming, extremely uncomfortable for the mother, and cannot normally be used during the early stages of labor.
A blood collecting device is disclosed in the U.S. Pat. No. 4,360,016 to Sarrine, issued Nov. 23, 1982. The blood collecting device includes a lancet and capillary tube carried together by an elongated member. The device positions the capillary tube adjacent the skin when the lancet is advanced by the member to puncture the skin. The entire instrument is moved to force the lancet to cut. In an environment such as the vagina, there is no means for shielding the capillary tube from contaminating fluids prior to contacting a fetus. A separate cone is used as a shield. The cone is first inserted and pressed against the fetal scale. The cone may cut off circulation to the isolated area making sampling difficult. Removal of the cone may return circulation to the lanced area thereby initiating excessive post sampling bleeding.
The U.S. Pat. No. 1,147,408 to Kells, issued July 20, 1915 discloses a trocar type device including means for providing a suction for drawing bodily fluid from a cavity through the puncturing trocar. The Kells patent also discloses no means for shielding the device prior to contact with the skin to be punctured. Nor could this device be applied trans-vaginally onto the fetal presenting part for the acquisition a fetal blood sample.
These prior art assemblies for lancing or puncturing skin and the drawing a blood or bodily fluid sample therefrom, when used alone, include no means for shielding the device from the environment nor do they include any means for retaining the assembly in place during the drawing of the blood sample. As disclosed in the Sarrine patent, a conventional endoscope must be used to provide a pathway through which the blood collecting device is used. This method uses a plurality of devices and still does not provide the desired environment.